Abstract
BackgroundTrypanosoma (Duttonella) vivax is a major pathogen of livestock in Africa and South America (SA), and genetic studies limited to small sampling suggest greater diversity in East Africa (EA) compared to both West Africa (WA) and SA.MethodsMultidimensional scaling and phylogenetic analyses of 112 sequences of the glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) gene and 263 sequences of the internal transcribed spacer of rDNA (ITS rDNA) were performed to compare trypanosomes from tsetse flies from Gorongosa National Park and Niassa National Reserve of Mozambique (MZ), wild ungulates and livestock from EA, and livestock isolates from WA and SA.ResultsMultidimensional scaling (MDS) supported Tvv (T. vivax) and TvL (T. vivax-like) evolutionary lineages: 1) Tvv comprises two main groups, TvvA/B (all SA and WA isolates plus some isolates from EA) and TvvC/D (exclusively from EA). The network revealed five ITS-genotypes within Tvv: Tvv1 (WA/EA isolates), Tvv2 (SA) and Tvv3–5 (EA). EA genotypes of Tvv ranged from highly related to largely different from WA/SA genotypes. 2) TvL comprises two gGAPDH-groups formed exclusively by EA sequences, TvLA (Tanzania/Kenya) and TvLB-D (MZ). This lineage contains more than 11 ITS-genotypes, seven forming the lineage TvL-Gorongosa that diverged from T. vivax Y486 enough to be identified as another species of the subgenus Duttonella. While gGAPDH sequences were fundamental for classification at the subgenus, major evolutionary lineages and species levels, ITS rDNA sequences permitted identification of known and novel genotypes.ConclusionsOur results corroborate a remarkable diversity of Duttonella trypanosomes in EA, especially in wildlife conservation areas, compared to the moderate diversity in WA. Surveys in wilderness areas in WA may reveal greater diversity. Biogeographical and phylogenetic data point to EA as the place of origin, diversification and spread of Duttonella trypanosomes across Africa, providing relevant insights towards the understanding of T. vivax evolutionary history.
Highlights
Trypanosoma (Duttonella) vivax is a major pathogen of livestock in SA South America (Africa) and South America (SA), and genetic studies limited to small sampling suggest greater diversity in East Africa (EA) compared to both West Africa (WA) and SA
Tsetse fly identification and prevalence of T. vivax and T. vivax-like determined by fluorescent fragment length barcoding (FFLB) Barcoded tsetse flies from Gorongosa National Park (GNP) and National Reserve (NNR) were identified as Glossina morsitans morsitans, which was the
Our comparative study of a large sample of T. vivax and T. vivax-like glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) and ITS internal transcribed spacer of rDNA (rDNA) sequences uncovered two major evolutionary lineages, constituted by several genotypes, within the subgenus Duttonella: T. vivax (Tvv) composed of five genotypes, and T. vivaxlike (TvL) constituted by TvL-Gorongosa, an assemblage of seven genotypes, in addition to genotypes that likely belong to other TvL lineages
Summary
Trypanosoma (Duttonella) vivax is a major pathogen of livestock in Africa and South America (SA), and genetic studies limited to small sampling suggest greater diversity in East Africa (EA) compared to both West Africa (WA) and SA. Animal African trypanosomiasis (AAT) caused by Trypanosoma (Duttonella) vivax is a major challenge to livestock production in sub-Saharan Africa [1]. This species is a highly prevalent livestock pathogen across the tsetse belt (cyclical transmission) [2,3,4,5], as well as in tsetse-free areas [6, 7]. Pathological lesions in various organs and nervous signs were reported in cattle that were experimentally infected with Ethiopian isolates of unknown genotypes [6]
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